Spinning wheel has pauses after each rotation?
Most likely, your keyframes are moving in bezier curves. This causes them to slow down at the beginning and end. You could try going into the Curve editor, selecting all of the keyframes on the curve that corresponds to the rotation of your wheel, key "T" and select linear on the left side of the pop-up menu. This will solve your problem.

Now, instead of continuing to add keyframes until the end of your animation, you can key "Shift+E" choose linear extrapolation, and the rotation will continue forever.

Hope this helps! Happy blending.